The present invention relates generally to an imaging apparatus and transfer components thereof for use in electrostatographic, including digital, apparatuses. The transfer components herein are useful for many purposes including removing toner from a charge retentive surface and transporting it to a final image substrate, transferring toner from a charge retentive surface to a bias charging member, and in transfuse applications wherein the toner is transferred and fused to a copy substrate. More specifically, the present invention relates to transfer components comprising a polyurethane film or layer which, in embodiments, is filled with a conductive filler in order to impart desired resistivity. In specific embodiments, the conductive filler is a doped metal oxide filler, preferably antimony doped tin oxide filler. In another embodiment, the transfer components comprise a substrate, and an outer polyurethane layer provided thereon. In yet another embodiment, the transfer components comprise a substrate, a polyurethane layer provided thereon, and an outer release layer provided on the polyurethane layer. The present invention may be useful in xerographic machines, including digital, for various applications, especially for color applications.
Examples of transfer members include those described in Buchan et al., U.S. Pat. No. 3,893,761, which discloses an intermediate transfer belt having a polyimide film substrate coated with 0.1 to 10 mils of silicone rubber or a fluoroelastomer. Berkes et al., U.S. Pat. No. 5,119,140, discloses a single layer intermediate transfer belt fabricated from clear Tedlar.RTM., carbon loaded Tedlar.RTM. or pigmented Tedlar.RTM.. Nisheise et al., U.S. Pat. No. 5,099,286, discloses an intermediate transfer belt comprising electrically conductive urethane rubber as the substrate (10.sup.3 to 10.sup.4 ohm-cm) and a layer of polytetrafluoroethylene. Bujese, U.S. Pat. No. 5,150,161, discloses suitable materials for laminate intermediate transfer members in a color printing apparatus. Bujese et al., U.S. Pat. No. 5,208,638, discloses an intermediate transfer surface employing a conductive fluoropolymer material. Mammino et al., U.S. Pat. No. 5,298,956, discloses a reinforced seamless intermediate transfer member having embedded in the reinforcing member, filler materials and an electrical property regulating material.
Yu et al., U.S. Pat. No. 5,303,014, discloses a bias transfer member comprising a layer of resistive material (10.sup.10 to 10.sup.15 ohms-cm) such as polyimide siloxane and polytetrafluoroethylene having fluorine atoms embedded therein. Eddy et al., U.S. Pat. No. 3,959,573 discloses biasable members having at least one layer of coating of a hydrophobic elastomeric polyurethane. Similarly, Seanor et al., U.S. Pat. No. 3,929,574 discloses biasable members having an elastomeric resilient polyurethane coating filled with ionic additives.
U.S. Pat. No. 5,576,818 discloses an intermediate transfer component having multiple coatings including a) an electrically conductive substrate, b) a conformable and electrically resistive layer comprised of a first polymeric material, and c) a toner release layer comprised of a second polymeric material. The substrate may be polyimide filled with carbon black, the intermediate layer may be fluoroelastomer, and the outer release layer may be a fluoroelastomer or fluorosilicone. U.S. Pat. No. 5,612,773 discloses a transfix configuration for a color apparatus.
It is desirable to provide a multifunctional transfer film that can be suitable for use in several areas in the electrostatographic transfer process such as intermediate transfer, bias transfer, and transfix. It is also desirable to provide such a film for use in liquid development production color machine employing image-on image technology.
For such a multifunctional transfer component, it is necessary to impart conductive properties to such components by addition of conductive fillers. Carbon black has been the chosen additive for imparting conductive properties in electrostatographic components. Carbon black is relatively inexpensive and very efficient in that a relatively small percentage can impart a high degree of conductivity. However, the blackness of this material makes it difficult and sometimes impossible to fabricate colored products with the desired level of conductivity. Further, components filed with carbon black have a tendency to slough and thereby contaminate their surroundings with black, conductive debris.
Many doped metal oxides offer significant advantages in both color and transparency when compared to carbon black. They are, however, relatively expensive and usually require higher dosages to achieve comparable levels of conductivity. In addition, dispersion of metal oxides can lead to short comings in surface roughness and particle size.
Therefore, a need remains for conductive transfer components for use in electrostatographic or digital machines, wherein the component possesses desired resistivity without the drawbacks of lack of transparency of the film or layer which may adversely affect use in color products. Further, a need remains for a conductive transfer component having conductive fillers which impart the desired resistivity without compromising surface roughness. Further, a need remains for films having improved mechanical properties to maintain film or belt integrity for improved flex life and image registration, improved electrical properties including a resistivity within the range desired for superior performance and to control electrostatic transfer functions, improved chemical stability to liquid developer or toner additives, improved thermal stability for transfix operations, improved conformability, low surface energy, and higher modulus. Further, a need exists for a film or component in which the resistivity is uniform and is relatively unaffected by changes in environmental conditions such as changes in humidity, temperature, electrical surges, and the like. Many of these objects have been met by various embodiments of the present invention.